FIBER-OPTIC CURRENT AND VOLTAGE METERS.

Sensors for fiber optic current and voltage meters have been developed by making use of the Faraday effect and the Pockels effect, respectively. For low-current detection, a newly developed mixed rare-earth iron garnet crystal of the composition of (Y//0//. //8//1Tb//0//. //1//9)//3 Fe//5O//1//2 is applied, while, for high current measurement, ZnSe crysal is used. The current sensors prepared with these materials cover the current induced magnetic field ranging from 0. 06 Oe to 1850 Oe. The optical output fluctuation is within plus or minus 1. 5% over the temperature range from minus 20 degree C to 120 degree C. The voltage sensor using LiNbO//3 crystal measures voltage from 0. 05v to 200v with an output fluctuation of plus or minus 1. 0% between the temperature of minus 20 degree C and 120 degree C. In this sensor, light is incident on the Z-face, and two opposite Z-faces with transparent electrodes are shorted to eliminate the disturbance of the pyroelectric effect.